The operation of an internal combustion engine with multiple injections (also referred to as “split injection”) is used, inter alia, for reducing particle emissions. In this context, the conventional injection of an individual fuel injection during the working cycle is replaced by the injection of a plurality of chronologically distributed fuel injections, wherein comparatively less fuel is used for each individual injection process than in the case of an individual injection.
However, a problem which occurs in practice in the case of multiple injections is that pressure waves which occur in the fuel line of systems with high fuel pressure during operation in a mode with multiple injections can cause the internal combustion engine to operate in an unstable fashion.
This instability is caused by undesired deviation in the actual injection quantity brought about by pressure pulsations in the common fuel line. Depending on the distribution and chronological arrangement of the multiple injections at all the cylinders, these high pressure pulsations can occur due to unfavorable superimposition of the excitation as a result of the respective extraction of fuel.
The inventors herein have recognized the above issues and provide a method to at least partly address them. In one embodiment, a method for operating an internal combustion engine having a plurality of cylinders comprises, during one working cycle, distributing fuel for each cylinder of the plurality of cylinders among a plurality of injection processes according to settable split factors which respectively define a setpoint fuel mass and/or injection duration and time setting of each respective injection process for the plurality of individual injection processes, wherein random variation is carried out for at least one injection process.
Thus, the method according to the disclosure for operating an internal combustion engine comprising a plurality of cylinders, during one working cycle, the fuel injection for each of the cylinders is distributed among a plurality of injection processes according to settable split factors which respectively define the setpoint fuel mass and/or the injection duration and the time setting of the respective injection process for the individual injection processes, wherein random variation is carried out for at least one injection process.
The present disclosure is based, in particular, on the concept of performing random variation of the split factors for individual injection processes within a range defined by a tolerance value during an operating mode of the internal combustion engine with multiple injections. By means of such a device or by increasing the splitting or apportioning of the fuel injection for the individual injection processes it is possible as a result to reduce the pressure waves within the fuel line. In this context, a reduction in pressure waves within the fuel line can already be achieved by marginal change in the split factors for each injection process and each cylinder.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.